Ink supply means for a printing machine

ABSTRACT

An ink supply unit for a receiving roller of a printing machine. The ink supply unit includes an ink rail mounted in close proximity to the surface of the receiving roller, and a plurality of ink reservoirs mounted one above the other in the ink rail that discharge differently colored inks in accordance with the printing requirements onto the surface of the receiving roller through a valve mechanism. Wiper rollers are mounted adjacent to the surface of the receiving roller to wipe the surface thereof to reduce ink wastage due to misting or the like. The inks are introduced onto the surface of the receiving roller and are mixed to form the required color for printing by the combined action of the wiper rollers and a roller train that links the receiving roller and the print roller in the printing machine.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to improvements in or relating to ink supplymeans for a printing machine and more particularly to an ink supplymeans which is capable of supplying at least three primary colored inksto a print roller surface in such a manner that they are mixed on theroller surface to form a desired color of ink for printing.

2. Description of the Prior Art

Conventionally, ink supply means in a printing machine are arranged soas to supply a single color of ink to a print roller. If it is desiredto change the color of ink for printing, usually the machine has to bestopped, the ink supply changed, and the printing roller cleaned. Ofcourse, this procedure is time-consuming and because the printingmachine is stopped, printing time is increased. Furthermore, since it isnot possible to change ink color without the necessity for the aboveactions to be taken, printing versatility is restricted. It is an objectof the present invention to provide a more versatile ink supply meanswherein at least two different colored inks, particularly two or threeprimary colors, can be supplied in predetermined relative quantities formixing prior to application to the surface of the print roller to giveany desired color.

SUMMARY OF THE INVENTION

According to the present invention, there is provided an ink supplymeans for a printing machine comprising an ink rail mounted so as toextend generally longitudinally of a receiving roller of the machine,and wiper rollers mounted adjacent a surface of the receiving roller towipe a surface thereof. The ink rail comprises at least two discrete inkstorage means connected to respective ink outlets in a face of the railadjacent a surface of the receiving roller and valve means associatedwith each outlet to regulate the flow of ink through each outlet. Thereceiving roller is linked to a print roller via a roller train. Theinks are mixed by the action of the wiper rollers and passage of the inkbetween rollers of the roller train.

With this arrangement it is possible to provide an ink supply meanswhich is more versatile in use, and which gives rise to an increasednumber of printing possibilities.

Preferably the ink rail has a generally curved end face which, in use,is mounted in close proximity to the surface of the receiving roller andgenerally conforms to the outer circumferential surface of the roller inorder to reduce ink wastage.

Preferably the ink storage means are disposed one above the other in theink rail in order to best utilize the available space in the rail.

Preferably a supply of ink from each reservoir through each respectiveoutlet is controlled by a solenoid-operated valve means under thecontrol of a central control unit. The central control unit may bemicroprocessor-based.

Preferably three ink storage means are provided, respective ones ofwhich store inks colored in the three primary colors, namely Cyan,Magenta and Yellow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagrammatic side view of one form of ink supply meansaccording to the present invention; and

FIG. 2 shows a diagrammatic plan view of a conventional printing machineincorporating the ink supply means of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is shown an ink supply unit 10 for areceiving roller 11 of a printing machine.

The ink supply unit 10 comprises an ink rail 12 having a generallyconcave end face 13 which conforms generally with the outercircumferential surface of the receiving roller 11. The ink rail 12 ismounted in close proximity to the surface of the receiving roller 11with a gap of 0.002-0.012" (0.00508-0.03048 mm) therebetween in order toprevent ink wastage. Wiper rollers 14 of the kind described in myco-pending UK Application No. 9311230.8 are mounted at a top and abottom of the ink rail 12 adjacent the concave surface 13 and aredisposed such that the outer circumferential surface 16 of each roller14 is spaced by 0.004-0.010" (0.01016-0.0254 mm) from the outer surfaceof the receiving roller 11. The wiper rollers 14 act to further reduceink wastage by ensuring a uniform layer of ink is formed on the outersurface of the roller 11, thereby preventing misting, and also assist inthe mixing of the inks applied to the surface of the roller 11.

Ink reservoirs 17 are provided on the ink rail 12 and extendsubstantially the entire longitudinal length thereof. In the embodimentshown in the drawings, three such reservoirs 17 are shown mounted oneabove the other. However, it will be appreciated that as many inkreservoirs can be provided as desired or as necessary, the number onlybeing limited by any restriction on the dimensions of the ink rail 12.

Each ink reservoir 17 has associated therewith a solenoid-operated valvemechanism 18 which controls flow of ink from the reservoir 17 through afeed passage 19 to an outlet 21 adjacent the surface of the receivingroller 11. Each valve mechanism 18 comprises a valve head 22 mounted ona shaft 23 which is movable away from the roller 11 against theresistance of a biasing spring 24. The shaft 23 extends through theinterior of an electromagnet 26 such that upon actuation of theelectromagnet 26, the shaft 23 moves away from the roller 11 against thebias of the biasing spring 24 moving the valve head 22 away from therespective feed passage 19, thereby allowing ink to flow from thereservoir 17 to the surface of the roller 11. The actuation of theelectromagnet 26 can be under the control of a central control unit 30which may be microprocessor-based, and thus the supply of ink from thereservoirs 17 to the surface of the roller 11 can be controlled veryaccurately.

FIG. 2 shows a schematic representation of the layout of a typicalprinting machine, for example one used in the newspaper industry. An inksupply unit 10 of FIG. 1 is mounted adjacent a receiving roller which islinked to a print roller 27 by a respective roller train 28. The printrollers 27 are mounted in close proximity to a paper mounting roller 29.The path of the paper through the printing machine is indicated by arrowX and as the paper passes around the mounting roller 29, the ink isapplied to the paper by each print roller 27. In a conventional printingmachine, each print roller would apply a single color ink only to thepaper (chosen usually from Cyan, Magenta or Yellow). However, with thepresent arrangement, the color of ink to be applied to the paper by eachprint roller can be changed easily and quickly in a manner to bedescribed hereinafter.

The ink supply unit 10 associated with each receiving roller 11 can, asdescribed above, under the control of central control unit 30, apply anypredetermined quantities of the inks contained in the reservoirs 17 tothe surface of the receiving roller 11. In the present embodiment, thethree primary colors (Cyan, Magenta and Yellow) are contained in threereservoirs. However, any number of reservoirs can be provided as desiredor as appropriate. Thus, for example, one or more additional reservoirscan be provided which can contain one or more additional colors, forexample Black, Gold, Silver, etc.

Thus, under the control of the control unit, predetermined quantities ofink for each reservoir are applied to the surface of each roller 11. Themixing of the different colored inks to form the ink of the desiredcolor is initiated by the action of wiper rollers 14. As described in myco-pending application described above, these rollers are driven so thatthe circumferential surfaces move in a direction opposite to the surfaceof the roller 11, and therefore act to wipe the surface of the roller.Therefore, the inks applied to the surface of the roller 11 in thevicinity of outlet 21 are mixed as a fine uniform layer of ink is formedon the surface of the roller 11 under the action of the wiper rollers14. Mixing of the inks is continued as the ink passes down each rollertrain 28 from the roller 11 to each print roller 29. The transfer of inkbetween each roller of the train ensures that the mixing of the inks isthorough by the time the inks are transferred to the print roller 27 forapplication to the paper during printing.

It is of course to be appreciated that using a conventional printingmachine of the type shown in FIG. 2 and with each ink supply unit 10being controlled by the control unit independently of all the othersupply units, the printing possibilities are increased significantly andtherefore the versatility is increased. Thus, for example, each inksupply unit 10 can supply a different mixed color ink or, alternatively,each ink supply unit can supply the identical single color ink.Furthermore, many variations on this are permitted and will be readilyappreciated by the skilled reader.

It is of course to be understood that the present invention is notintended to be restricted to the details of the above embodiment, whichare described by way of example only.

What is claimed is:
 1. Ink supply means for a printing machine having areceiver roller, a roller train and a print roller, said receivingroller being linked to said print roller via said roller train, said inksupply means comprising an ink rail mounted so as to extend generallylongitudinally of a receiving roller of the machine, wiper rollersmounted adjacent a surface of the receiving roller to wipe a surfacethereof, said ink rail comprising at least two discrete ink storagemeans connected to respective ink outlets in a face of said railadjacent a surface of the receiving roller and valve means associatedwith each said outlet to regulate flow of ink through each said outlet,said inks being mixed by the action of said wiper rollers and passage ofthe ink between rollers of said roller train.
 2. Ink supply meansaccording to claim 1 wherein said ink rail has a generally curved endface which, in use, is mounted in close proximity to the surface of thereceiving roller and generally conforms to the outer circumferentialsurface of the roller in order to reduce ink wastage.
 3. Ink supplymeans according to claim 1 wherein when said rail is mountedsubstantially horizontally, said ink storage means are disposed oneabove the other in said ink rail in order to best utilize the availablespace in the rail.
 4. Ink supply means according to claim 1 furthercomprising a solenoid-operated valve associated with each ink storagemeans and a central control unit, wherein the supply of ink from eachink storage means through each respective outlet is controlled by saidsolenoid-operated valve under the control of said central control unit.5. Ink supply means according to claim 4 wherein the central controlunit is microprocessor-based.
 6. Ink supply means according to claim 1wherein three ink storage means are provided for storing inks colored inthe three primary colors Cyan, Magenta and Yellow, respectively.